U.S. patent number 4,160,751 [Application Number 05/855,765] was granted by the patent office on 1979-07-10 for low pressure injection moldable compositions.
This patent grant is currently assigned to Exxon Research & Engineering Co.. Invention is credited to Jan Bock, Robert D. Lundberg, Henry S. Makowski.
United States Patent |
4,160,751 |
Bock , et al. |
July 10, 1979 |
Low pressure injection moldable compositions
Abstract
This invention relates to injection moldable type elastomeric
compositions having a viscosity at 200.degree. C. at 0.73
sec.sup.-1 of less than about 8.times.10.sup.4 poises. The
compositions used for elastomeric articles include 100 parts of a
neutralized sulfonated EPDM terpolymer; about 25 to about 150 parts
per hundred of a non-polar process oil; about 25 to about 200 parts
per hundred of a filler; and a preferential plasticizer at about
less than 50 parts per hundred based on 100 parts of the sulfonated
elastomeric polymer. The composition may also include a crystalline
polyolefinic thermoplastic at least than about 100 parts per
hundred by weight. These blend compositions can be readily
processed due to their superior rheological properties on
conventional plastic fabrication equipment, especially on low
pressure injection molding equipment into elastomeric articles
having excellent physical properties and desirable rubbery
characteristics.
Inventors: |
Bock; Jan (Houston, TX),
Lundberg; Robert D. (Bridgewater, NJ), Makowski; Henry
S. (Scotch Plains, NJ) |
Assignee: |
Exxon Research & Engineering
Co. (Florham Park, NJ)
|
Family
ID: |
25322009 |
Appl.
No.: |
05/855,765 |
Filed: |
November 29, 1977 |
Current U.S.
Class: |
524/300; 524/238;
524/394; 524/398; 524/400; 260/DIG.31; 524/322; 524/399 |
Current CPC
Class: |
C08L
23/32 (20130101); C08L 23/32 (20130101); C08L
2666/02 (20130101); Y10S 260/31 (20130101) |
Current International
Class: |
C08L
23/00 (20060101); C08L 23/32 (20060101); C08L
091/00 () |
Field of
Search: |
;260/79.3R,42.33,42.47,33.6AQ,33.6PQ,28.5B,878B,879R,DIG.31 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Jacobs; Lewis T.
Attorney, Agent or Firm: Nanfeldt; Richard E.
Claims
What is claimed is:
1. An elastomeric composition having a viscosity at 0.73 sec.sup.-1
at 200.degree. C. of less than about 8.times.10.sup.4, and greater
than 5.times.10.sup.3 poises, said composition injection moldable
into an elastomeric article, which consists essentially of:
(a) a neutralized sulfonated elastomeric polymer having a viscosity
at 0.73 sec.sup.-1 at 200.degree. C. of about 3.times.10.sup.5
poises to about 5.times.10.sup.6 poises and about 15 to about 50
meq. neutralized metal sulfonate groups per 100 grams of said
neutralized sulfonated elastomeric polymer;
(b) about 25 to about 150 parts by weight of a non-polar process
oil per 100 parts by weight of said neutralized sulfonated
elastomeric polymer, said non-polar process oil having less than
about 2 wt. % polar type compounds therein;
(c) about 25 to about 300 parts by weight of an inorganic filler
per 100 parts by weight of said neutralized sulfonated elastomeric
polymer, said inorganic filler being selected from the group
consisting of clay, talc, and calcium carbonate and mixtures
thereof, a ratio of said inorganic filler to said non-polar process
oil being about 0.6 to about 1.25, and
(d) at least 8 parts by weight of a preferential ionic plasticizer
per 100 parts by weight of said neutralized sulfonated elastomeric
polymer, said preferential plasticizer having a melting point of at
least 25.degree. C. and is selected from the group consisting of
carboxylic acids having about 5 to about 30 carbon atoms and salts
of said carboxylic acids and mixtures thereof, an ion of said salt
being selected from the group consisting of aluminum, ammonium,
lead, Cd, Hg, and Groups IA, IIA and IB of the Periodic Table of
Elements.
2. A composition according to claim 1, wherein said neutralized
sulfonated elastomeric polymer is formed from an elastomeric
polymer selected from the group consisting of Butyl rubber and an
EPDM terpolymer.
3. A composition according to claim 2, wherein said EPDM terpolymer
consists essentially of about 40 to about 75 wt. % of ethylene, of
about 10 to about 53 wt. % of propylene and of about 1 to about 10
wt. % of a non-conjugated diene.
4. A composition according to claim 1, wherein said sulfonate
groups are neutralized with a counterion being selected from the
group consisting of ammonium, antimony, aluminum, lead and Groups
I-A, II-A, I-B and II-B of the Periodic Table of Elements and
mixtures thereof.
5. A composition according to claim 5, wherein said non-conjugated
diene is selected from the group consisting of 1,4-hexadiene,
dicyclopentadiene, alkylidene substituted norbornenes, alkenyl
substituted norbornenes and tetrahydroindenes.
6. A composition according to claim 5, wherein said non-conjugated
diene is 5-ethylidene-2-norbornene.
7. A composition according to claim 1, having a Shore Hardness A of
about 45 to about 70.
8. A composition according to claim 1, wherein said preferential
plasticizeris a combination of stearic acid and a metallic salt of
said stearic acid, a metal ion of said metallic salt being selected
from the group consisting of lead, antimony, aluminum, and Groups
I-A, II-A, I-B and II-B of the Periodic Table of Elements and
mixtures thereof.
9. A composition according to claim 1, wherein said filler has a
particle size of about 0.03 to about 20 microns.
10. A composition according to claim 1, wherein said filler has an
oil absorption of about 10 to about 100.
11. A composition according to claim 1, wherein said non-polar
process oil is selected from the group consisting of paraffinic,
naphthenic or aromatics and mixtures thereof.
12. A composition according to claim 1, wherein said non-polar
process oil is paraffinic having an Mn of about 400 to about
1000.
13. An elastomeric composition according to claim 1, wherein said
non-polar process oil is a paraffinic oil.
14. An elastomeric composition having a viscosity at 0.73
sec.sup.-1 at 200.degree. C. of about 5.times.10.sup.3 to about
8.times.10.sup.4 poises, said composition formable by extrusion or
injection molding into an elastomeric article, which consists
essentially of:
(a) a neutralized sulfonated elastomeric polymer having a viscosity
at 0.73 sec.sup.-1 at 200.degree. C. of about 3.times.10.sup.5
poises to about 5.times.10.sup.6 poises and about 15 to about 50
meq. neutralized sulfonate groups per 100 grams of said neutralized
sulfonated elastomeric polymer;
(b) about 25 to about 150 parts by weight of a non-polar process
oil per 100 parts by weight of said neutralized sulfonated
elastomeric polymer, said non-polar process oil having less than
about 2 wt. % polar type compounds therein;
(c) about 25 to about 300 parts by weight of an inorganic filler
per 100 parts by weight of said neutralized sulfonated elastomeric
polymer, said inorganic filler being selected from the group
consisting of clay, talc, and calcium carbonate and mixtures
thereof, a ratio of said inorganic filler to said non-polar process
oil being about 0.6 to about 1.25; and
(d) at least 8 parts by weight of a preferential plasticizer per
one hundred parts by weight of said neutralized sulfonated
elastomeric polymer, said preferential plasticizer being a mixture
of a carboxylic acid having about 5 to about 30 carbon atoms and
zinc stearate.
15. A composition according to claim 14 wherein said neutralized
sulfonated elastomeric polymer is formed from an elastomeric
polymer selected from the group consisting of Butyl rubber and an
EPDM terpolymer.
16. A composition according to claim 14 wherein said EPDM
terpolymer consists essentially of about 40 to about 75 wt. % of
ethylene, of about 10 to about 53 wt. % of propylene and of about 2
to about 10 wt. % of a non-conjugated diene.
17. A composition according to claim 16 wherein said non-conjugated
diene is selected from the group consisting of 1,4-hexadiene,
dicyclopentadiene, 5-alkylidene-2-norbornenes,
5-alkenyl-2-norbornenes and tetrahydroindene.
18. A composition according to claim 17 wherein said non-conjugated
diene is 5-ethylidene-2-norbornene.
19. An elastomeric article formed from an elastomeric composition
consisting essentially of:
(a) a neutralized sulfonated elastomeric polymer having a viscosity
at 0.73 sec.sup.- 1 at 200.degree. C. of about 3.times.10.sup.5
poises to about 5.times.10.sup.6 poises and about 15 to about 50
meq. neutralized sulfonate groups per 100 grams of said neutralized
sulfonated elastomeric polymer;
(b) about 25 to about 150 parts by weight of a non-polar process
oil per 100 parts by weight of said neutralized sulfonated
elastomeric polymer, said non-polar process oil having less than
about 2 wt. % polar type compounds therein;
(c) about 25 to about 300 parts by weight of an inorganic filler
per 100 parts by weight of said neutralized sulfonated elastomeric
polymer, said inorganic filler being selected from the group
consisting of clay, talc, and calcium carbonate and mixtures
thereof, a ratio of said inorganic filler to said non-polar process
oil being about 0.6 to about 1.25; and
(d) at least 8 parts by weight of a preferential ionic plasticizer
per 100 parts by weight of said neutralized sulfonated elastomeric
polymer, said preferential plasticizer having a melting point of at
least 25.degree. C. and is selected from the group consisting of
carboxylic acids having about 5 to about 30 carbon atoms and salts
of said carboxylic acids and mixtures thereof, an ion of said salt
being selected from the group consisting of aluminum, ammonium,
lead, Cd, Hg, and Groups IA, IIA and IB of the Periodic Table of
Elements.
20. An elastomeric article according to claim 19, wherein said
neutralized sulfonated elastomeric polymer is formed from an
elastomeric polymer selected from the group consisting of Butyl
rubber and an EPDM terpolymer.
21. An elastomeric article according to claim 19, wherein said
sulfonated groups are neutralized with a counterion being selected
from the group consisting of antimony, iron, aluminum, lead and
Groups IA, IIA, IB and IIB of the Periodic Table of Elements and
mixtures thereof.
22. An elastomeric article according to claim 20, wherein said EPDM
terpolymer consists of about 40 to about 75 wt. % ethylene, of
about 10 to about 53 wt. % of propylene, and of about 2 to about 10
wt. % of a conjugated diene.
23. An elastomeric article according to claim 22, wherein said
non-conjugated diene is selected from the group consisting of
1,4-hexadiene, dicyclopentadiene, 5-alkylidene-2- norbornenes,
5-alkenyl-2-norbornenes and tetrahydroindene.
24. An elastomeric article formed from an elastomeric composition
consisting essentially of:
(a) a neutralized sulfonated elastomeric polymer having a viscosity
at 0.73 sec.sup.-1 at 200.degree. C. of about 3.times.10.sup.5
poises to about 5.times.10.sup.6 poises and about 15 to about 50
meq. neutralized sulfonate groups per 100 grams of said neutralized
sulfonated elastomeric polymer;
(b) about 25 to about 150 parts by weight of a non-polar process
oil per 100 parts by weight of said neutralized sulfonated
elastomeric polymer, said non-polar process oil having less than
about 2 wt. % polar type compounds therein;
(c) about 25 to about 300 parts by weight of an inorganic filler
per 100 parts by weight of said neutralized sulfonated elastomeric
polymer, said inorganic filler being selected from the group
consisting of clay, talc, and calcium carbonate and mixtures
thereof, a ratio of said inorganic filler to said non-polar process
oil being about 0.6 to about 1.25; and
(d) at least 8 parts by weight of a preferential plasticizer per
one hundred parts by weight of said neutralized sulfonated
elastomeric polymer, said preferential plasticizer being a mixture
of a carboxylic acid having about 5 to about 30 carbon atoms and
zinc stearate.
25. An elastomeric article according to claim 24, wherein said
neutralized sulfonated elastomeric polymer is formed from an
elastomeric polymer selected from the group consisting of Butyl
rubber and an EPDM terpolymer.
26. An elastomeric article according to claim 25, wherein said EPDM
terpolymer consists of about 40 to about 75 wt. % ethylene, of
about 10 to about 53 wt. % of propylene, and of about 2 to about 10
wt. % of a conjugated diene.
27. An elastomeric article according to claim 26, wherein said
non-conjugated diene is selected from the group consisting of
1,4-hexadiene, dicyclopentadiene, 5-alkylidene-2-norbornenes,
5-alkenyl-2-norbornenes and tetrahydroindene.
Description
FIELD OF THE INVENTION
This invention relates to injection moldable type elastomeric
compositions having a viscosity at 200.degree. C. at 0.73
sec.sup.-1 of less than about 8.times.10.sup.4 poises. The
compositions used for elastomeric articles include 100 parts of a
neutralized sulfonated EPDM terpolymer; about 25 to about 150 parts
per hundred of a non-polar process oil; about 25 to about 200 parts
per hundred of a filler; and a preferential plasticizer at about
less than about 50 parts per hundred based on 100 parts of the
sulfonated elastomeric polymer. The composition may also include a
crystalline polyolefinic thermoplastic at less than about 100 parts
per hundred by weight.
These blend compositions can be readily processed due to their
superior rheological properties on conventional plastic fabrication
equipment, especially on low pressure injection molding equipment
into elastomeric articles having excellent physical properties and
desirable rubbery characteristics.
BACKGROUND OF THE INVENTION
Recently, a new class of thermoelastic sulfonated polymers has been
described in a number of U.S. patents. These sulfonated polymers
are derived from polymeric materials having olefinic unsaturation,
especially elastomeric polymers such as Butyl and EPDM rubbers.
U.S. Pat. No. 3,642,728, herein incorporated by reference, clearly
teaches a method of selective sulfonation of olefinic unsaturation
sites of an elastomeric polymer to form an acid form of a
sulfonated elastomeric polymer. The olefinic sites of the
elastomeric polymer are sulfonated by means of a complex of a
sulfur trioxide donor and a Lewis base. The SO.sub.3 H groups of
the sulfonated elastomer can be readily neutralized with a basic
material to form an ionically cross-linked elastomer having
substantially improved physical properties over an unsulfonated
elastomer at room temperature. However, these ionically
cross-linked elastomers may be processed like a conventional
thermoplastic at elevated temperatures under a shear force in the
presence of selected preferential plasticizers which dissipate the
ionic associations at the elevated temperatures thereby creating a
reprocessable elastomer.
The basic materials used as neutralizing agents are selected from
organic amines or basic materials selected from Groups I, II, III,
IV, V, VIB, VIIB and VIII and mixtures thereof of the Periodic
Table of Elements. Although these sulfonated elastomeric polymers
prepared by the process of this patent are readily useable in a
certain number of limited applications, they are not as readily
adaptable for the manufacture of an injection moldable elastomeric
article such as footwear as are the improved compositions of the
present invention, wherein both improved physical and rheological
properties are realized.
U.S. Pat. No. 3,836,511, herein incorporated by reference, teaches
an improved process for the sulfonation of the olefinic sites of
the elastomeric polymer, wherein the improved sulfonating agent is
selected from acetyl sulfate, propionyl sulfate and butyryl
sulfate. The neutralizing agents employed to neutralize the acid
form of the sulfonated elastomeric polymers are organic amines. The
resultant ionically cross-linked sulfonated elastomers prepared by
this process do not exhibit both the improved physical and
rheological properties of the compositions of the present
invention.
U.S. Pat. No. 3,870,841, herein incorporated by reference, teaches
a method of plasticization of the polymeric backbone of a
neutralized sulfonated plastic polymer by means of a polymer chain
plasticizer which is a liquid compound having a boiling point of at
least about 120.degree. F. The polymer chain plasticizer is
selected from a dialkyl phthalate, a process oil or an organic acid
ester. Additionally, a domain plasticizer can be incorporated into
the composition, wherein the domain plasticizer reversibly disrupts
the association of the sulfonate groups at a temperature of
forming. The compositions formed by this process are not as
suitable for the manufacture of high performance elastomeric
articles such as footwear formed by an injection molding process as
are the compositions of the present invention.
U.S. Pat. No. 3,847,854, herein incorporated by reference, teaches
a method of improving the processability of neutralized sulfonated
elastomeric polymers by the addition of a preferential plasticizer
which has at least one functional constituent which exhibits a bond
moment whose absolute value is at least 0.6 Debyes, and must be a
liquid at the desired processing temperature of the neutralized
sulfonated elastomeric polymer. Again, the compositions of the
present invention are more adaptable for use in the manufacture of
high performance elastomeric articles.
Products resulting from the aforementioned methods for obtaining
neutralized sulfonated elastomeric compositions, possess either
unsuitable rheological or physical properties for the applications
envisioned in the present invention.
For example, the physical properties of these resultant sulfonated
elastomeric products of these aforementioned patents are unsuitable
for a major application of an injection molding process, namely the
manufacture of footwear, wherein excellent resilience, dimensional
stability, excellent low and high temperature flexibility,
excellent flex fatique, and excellent abrasion are needed.
Furthermore, the high melt viscosity and melt elasticity of these
materials makes injection molding difficult if not impossible.
These materials of the aforementioned patents which are generally
processable by only compression molding have unsuitable physical
properties for this major application of footwear.
The materials cost of the compositions of the instant invention is
substantially reduced over those of the aforementioned patents,
wherein these previous patents failed to realize the criticality of
the proper selection of the chemical and physical uniqueness of the
basic elastomeric backbone, the degree of sulfonation, the proper
selection of neutralizing agent in conjunction with plasticization,
and the ability to extend these sulfonated polymers with oils and
fillers. Unsulfonated elastomers, when extended with oils and
fillers, show a general deterioration in physical and rheological
properties as is clearly shown in the Detailed Description of the
present invention. Quite surprisingly, through the proper selection
of oil and filler within a critical ratio of filler to oil, the
sulfonated elastomeric compositions of the present invention show a
marked improvement in both rheological and physical properties.
U.S. Pat. application Nos. 542,502 and 524,512 filed on Nov. 18,
1974, describe the blending of a crystalline polyolefinic material
with a neutralized sulfonated elastomeric polymer in an attempt to
improve both the rheological and physical properties of the
elastomeric polymer. The selection of the use of the crystalline
polyolefinic material to improve both the stiffness as well as
improving the melt viscosity of the composition was based in part
upon the limitation of the use of fillers such as carbon black,
clays, calcium carbonate or silicates as a single additive to the
elastomeric polymer. Although fillers in combination with an
elastomeric polymer increase the hardness of the composition, these
fillers deteriorate the melt viscosity of the resultant
composition. These materials are more adaptable for stiff
elastomeric articles such as rubberized chair tips or wheels
whereas the compositions of the present invention are more adapted
for flexible elastomeric articles such as elastomeric footwear.
The unique and novel improved compositions of the present invention
overcome the deficiencies of the aforementioned U.S. Patents and
applications from both a rheological and physical properties
aspect. The blend compositions of the present invention solve the
problem of having a material which has both desirable rheological
and physical properties for the manufacture of an elastomeric
article as an elastomeric footwear, wherein the extrudate of the
resultant compositions do not exhibit melt fracture during
extrusion processing as in the case in some of the aforementioned
patents.
SUMMARY OF THE INVENTION
It has been found surprisingly that compositions formed from blends
of neutralized sulfonated elastomeric materials, in particular a
select class of neutralized sulfonated elastomeric polymers,
inorganic fillers, a non-polar process oil and a preferential
plasticizer have suitable rheological and physical properties for
the formation of an elastomeric article, namely a footwear, by a
low pressure injection molding process.
Accordingly, it is an object of our present invention to provide
unique and novel compositions of matter for producing a high
performance elastomeric article by a low pressure injection molding
process, wherein the compositions of the elastomeric article have a
viscosity at 0.73 sec.sup.-1 at 200.degree. C. of less than about
8.times.10.sup.4 poises, and a Shore A Hardness of about 45 to
about 85.
It is the object of the instant invention to describe a class of
compounds based on sulfonated ethylenepropylene terpolymers which
can be processed on plastics type extrusion equipment at high rates
and which possess improved physical characteristics such as
abrasion, flexibility and rubbery feel. One of the essential
aspects of the present invention comprises the discovery that only
a restricted class of the subject sulfonated elastomers may be
readily employed for low pressure injection molding fabrication.
The restrictions are primarily associated with processing and
product performance characteristics. These characteristics are to a
degree modulated by the type and concentration of various
compounding ingredients. The compositions of the instant invention
will, therefore, involve a class of compositions based on a
restrictive class of sulfonated elastomers.
A substantial segment of the plastics and rubber fabrication
industry employs a fabrication technique known as low pressure
injection molding to form articles which can be classified as
injection molded articles. As application employing this
fabrication technique is elastomeric footwear which requires
materials which are flexible and tough. Two broad classifications
of materials which have been used are vulcanized elastomers and
plasticized thermoplastics such as polyvinyl chloride (PVC). The
fabrication of injection molded articles based on vulcanized
elastomers is a major item of cost involving the vulcanization
procedure. Not only is this step costly from an energy intensive
viewpoint, but it is time consuming. The use of plasticating
injection molding equipment for thermoplastic materials is more
economical and results in high production rates for materials such
as plasticized PVC. While these materials possess a degree of
flexibility, they do not have a good rubbery feel or good low
temperature flexibility. It is therefore desirable to have
materials which can be processed on plastics type injection molding
equipment at conventional plastics rates and which possess the
flexibility and subjective rubbery characteristics of vulcanized
elastomers.
GENERAL DESCRIPTION
This present invention relates to unique and novel blend
compositions of a neutralized sulfonated elastomeric polymer, an
inorganic filler, and a non-polar process oil, wherein the
resultant composition has a viscosity at 0.73 sec.sup.-1 at
200.degree. C. of less than about 8.times.10.sup.4 poises, wherein
the compositions are readily processable in a conventional
injection molding process into a high performance elastomeric
article such as footwear. The resultant elastomeric article has
excellent low and elevated temperature flexibility, excellent
abrasion resistance, excellent flex fatique, superior dimensional
stability, good resilience, and a rubber-like feel, and a Shore A
Hardness of about 45 to about 85.
Various critically selected additives can be incorporated into the
blend compositions such as a polyolefin thermoplastic for further
modification of hardness as well as rheological properties, a
whitening pigment, a lubricant for improvement of the physical
appearance such as shine of the finished footwear as well as the
ability to easily eject the formed article from the mold during the
injection molding process and a reinforcing filler such as silica
or carbon black, wherein the reinforcing filler constitutes a minor
portion of the composition.
The neutralized sulfonated elastomeric polymer of this present
instant invention are derived from unsaturated polymers which
include low unsaturated elastomeric polymers such as Butyl rubber,
or EPDM terpolymers.
Alternatively, other unsaturated polymers are selected from the
group consisting essentially of partially hydrogenated
polyisoprenes, partially hydrogenated polybutadienes, Neoprene,
styrene-butadiene copolymers of isoprene-styrene random
copolymers.
The expression "Butyl rubber" as employed in the specification and
claims is intended to include copolymers made from a polymerization
reaction mixture having therein from 70 to 99.5% by weight of an
isoolefin which has about 4 to 7 carbon atoms, e.g. isobutylene and
about 0.5 to 30% by weight of a conjugated multiolefin having from
about 4 to 14 carbon atoms, e.g. isoprene. The resulting copolymer
contains 85 to 99.8% by weight of combined isoolefin and 0.2 to 15%
of combined multiolefin.
Butyl rubber generally has a Staudinger molecular weight of about
20,000 to about 500,000, preferably about 25,000 to about 400,000,
especially about 100,000 to about 400,000, and a Wijs Iodine No. of
about 0.5 to 50, preferably 1 to 15. The preparation of Butyl
rubber is described in U.S. Pat. No. 2,356,128 which is
incorporated herein by reference.
For the purposes of this invention, the Butyl rubber may have
incorporated therein from about 0.2 to 10% of combined multiolefin;
preferably about 0.5 to about 6%; more preferably about 1 to about
4%, e.g. 2%.
Illustrative of such a Butyl rubber is Exxon Butyl 365 (Exxon
Chemical Co.), having a mole percent unsaturation of about 2.0% and
a Mooney viscosity (ML, 1+3, 212.degree. F.) of about 40-50.
Low molecular weight Butyl rubbers, i.e. Butyl rubbers having a
viscosity average molecular weight of about 5,000 to 85,000 and a
mole percent unsaturation of about 1 to about 5% may be sulfonated
to produce the polymers useful in this invention. Preferably, these
polymers have a viscosity average molecular weight of about 25,000
to about 60,000.
The EPDM terpolymers are low unsaturated polymers having about 1 to
about 10.0 wt. % olefinic unsaturation, more preferably about 2 to
about 8, most preferably about 3 to 7 defined according to the
definition as found in ASTM-D1418-64 and is intended to mean
terpolymers containing ethylene and propylene in the backbone and a
diene in the side chain. Illustrative methods for producing these
terpolymers are found in U.S. Pat. No. 3,280,082, British Pat. No.
1,030,289 and French Pat. No. 1,386,600, which are incorporated
herein by reference. The preferred polymers contain about 40 to
about 80 wt. % ethylene and about 1 to about 10 wt. % of a diene
monomer, the balance of the polymer being propylene. Preferably,
the polymer contains about 50 to about 70 wt. % ethylene, e.g. 50
wt. % and about 2.6 to about 8.0 wt. % diene monomer, e.g. 5.0 wt.
%. The diene monomer is preferably a non-conjugated diene.
Illustrative of these non-conjugated diene monomers which may be
used in the terpolymer (EPDM) are 1,4-hexadiene, dicyclopentadiene,
5-ethylidene-2-norbornene, 5-methylene-2-norbornene,
5-propenyl-2-norbornene, and methyl tetrahydroindene.
A typical EPDM is Vistalon 2504 (Exxon Chemical Co.), a terpolymer
having a Mooney viscosity (ML, 1+8, 212.degree. F.) of about 40 and
having an ethylene content of about 40 wt. % and a
5-ethylidene-2-norbornene content of about 5.0 wt. %. The Mn of
Vistalon 2504 is about 47,000, the Mv is about 145,00 and the Mw is
about 174,000.
Another EPDM terpolymer Vistalon 2504-20 is derived from V-2504
(Exxon Chemical Co.) by a controlled extrusion process, wherein the
resultant Mooney viscosity at 212.degree. F. is about 20. The Mn of
Vistalon 2504-20 is about 26,000, the Mv is about 90,000 and the Mw
is about 125,000.
Nordel 1320 (DuPont) is another terpolymer having a Mooney
viscosity at 212.degree. F. of about 25 and having about 53 wt. %
of ethylene, about 3.5 wt. % of 1,4-hexadiene, and about 43.5 wt. %
of propylene.
The EPDM terpolymers of this invention have a number average
molecular weight (Mn) of about 10,000 to about 200,000, more
preferably of about 15,000 to about 100,000, and most preferably of
about 20,000 to about 60,000. The Mooney viscosity (ML, 1+8,
212.degree. F.) of the EPDM terpolymer is about 5 to about 60, more
preferably about 10 to about 50, most preferably about 15 to about
40. The Mv of the EPDM terpolymer is preferably below about 350,000
and more preferably below about 300,000. The Mw of the EPDM
terpolymer is preferably below about 500,000 and more preferably
below about 350,000.
In carrying out the invention, the elastomeric polymer is dissolved
in a non-reactive solvent such as a chlorinated aliphatic
hydrocarbon, chlorinated aromatic hydrocarbon, an aromatic
hydrocarbon, or an aliphatic hydrocarbon such as carbon
tetrachloride, dichloroethane, chlorobenzene, benzene, toluene,
xylene, cyclohexane, pentane, isopentane, hexane, isohexane, or
heptane. The preferred solvents are the lower boiling aliphatic
hydrocarbons. A sulfonating agent is added to the solution of the
elastomeric polymer and non-reactive solvent at a temperature of
about -100.degree. C. to about 100.degree. C. for a period of time
of about 1 to about 60 minutes, most preferably at room temperature
for about 5 to about 45 minutes; and most preferably about 15 to
about 30. Typical sulfonating agents are described in U.S. Pat.
Nos. 3,642,728 and 3,836,511, previously incorporated herein by
reference. These sulfonating agents are selected from an acyl
sulfate, a mixture of sulfuric acid and an acid anhydride or a
complex of a sulfur trioxide donor and a Lewis base containing
oxygen, sulfur, or phosphorous. Typical sulfur trioxide donors are
SO.sub.3, chlorosulfonic acid, fluorosulfonic acid, sulfuric acid,
oleum, etc. Typical Lewis bases are: dioxane, tetrahydrofuran,
tetrahydrothiophene, or triethylphosphate. The most preferred
sulfonation agent for this invention is an acyl sulfate selected
from the group consisting essentially of benzoyl, acetyl, propionyl
or butyryl sulfate. The acyl sulfate. The acyl sulfate can be
formed in situ in the reaction medium or pregenerated before its
addition to the reaction medium in a chlorinated aliphatic or
aromatic hydrocarbon.
It should be pointed out that neither the sulfonating agent nor the
manner of sulfonation is critical, provided that the sulfonating
method does not degrade the polymer backbone. The reaction is
quenched with an aliphatic alcohol such as methanol, ethanol,
isopropanol, with an aromatic hydroxyl compound, such as phenol, a
cyclo aliphatic alcohol such as a cyclohexanol or with water. The
acid form of the sulfonated elastomeric polymer has about 10 to
about 100 meq. SO.sub.3 H groups per 100 grams of sulfonated
polymer, more preferably about 15 to about 50, and most preferably
about 20 to about 40. The meq. of SO.sub.3 H/100 grams of polymer
is determined by both titration of the polymeric sulfonic acid and
Dietert Sulfur analysis. In the titration of the sulfonic acid, the
polymer is dissolved in solvent consisting of 95 parts of toluene
and 5 parts of methanol at a concentration level of 50 grams per
liter of solvent. The acid form is titrated with ethanolic sodium
hydroxide to an Alizarin Thymolphthalein endpoint.
The acid form of the sulfonated polymer is gel free and
hydrolytically stable. Gel is measured by stirring a given weight
of polymer in a solvent comprised of 95 toluene/5 methanol at a
concentration of 5 wt. % for 24 hours, allowing the mixture to
settle, withdrawing a weighed sample of the supernatant solution
and evaporating to dryness.
Hydrolytically stable means that the acid function in this case the
sulfonic acid, will not be eliminated under neutral or slightly
basic conditions to a neutral moiety which is incapable of being
converted to highly ionic functionality.
Neutralization of the acid form of the sulfonated elastomeric
polymer is done by the addition of a solution of a basic salt to
the acid form of the sulfonated elastomeric polymer dissolved in
the mixture of the aliphatic alcohol and non-reactive solvent. The
basic salt is dissolved in a binary solvent system consisting of
water and/or an aliphatic alcohol. The counterion of the basic salt
is selected from antimony, aluminum, lead or Groups I-A, II-A, I-B
or II-B of the Periodic Table of Elements and mixtures thereof. The
anion of the basic salt is selected from a carboxylic acid having
from about 1 to 4 carbon atoms, a hydroxide or alkoxide and
mixtures thereof. The preferred neutralizing agent is a metal
acetate, more preferably zinc acetate. Sufficient metal salt of the
carboxylic acid is added to the solution of the acid form of the
elastomeric polymer to effect neutralization. It is preferable to
neutralize at least 95% of the acid groups, more preferably about
98%, most preferably 100%.
Examples of metal ozides useful in preparing metal sulfonates are
MgO, CaO, BaO, ZnO, Ag.sub.2 O, PbO.sub.2 and Pb.sub.3 O.sub.4.
Useful examples of metal hydroxides are NaOH, KOH, LiOH,
Mg(OH).sub.2 and Ba(OH).sub.2. The resultant neutralized sulfonated
terpolymer has a viscosity at 0.73 sec.sup.-1 at 200.degree. C. of
about 3.times.10.sup.5 poises to about 5.times.10.sup.6 poises,
more preferably of about 3.times.10.sup.5 poises to about
3.times.10.sup.6 poises and most preferably about 5.times.10.sup.5
poises to about 3.0.times.10.sup.6 poises.
A means of characterizing the apparent molecular weight of a
polymer involves the use of melt rheological measurements. For
ionic polymers, this is the preferred method since solution
techniques are difficult to interpret due to the complex nature of
the ionic associations. Melt rheological measurements of apparent
viscosity at a controlled temperature and shear rate can be used as
a measure of apparent molecular weight of an ionic polymer.
Although the exact relationship between melt viscosity and apparent
molecular weight for these ionic systems is not known, for the
purposes of this invention the relationship will be assumed to be
one of direct proportionality. Thus, in comparing two materials,
the one with the higher melt viscosity will be associated with the
higher apparent molecular weight.
The melt viscosity of the systems investigated were determined by
the use of an Instron Capillary Rheometer. Generally, the melt
viscosity measurements were made at a temperature of 200.degree. C.
and at various shear rates corresponding to crosshead speeds from
0.005 in/min to 20 in/min. The apparent viscosity at 200.degree. C.
and at a shear rate of 0.73 sec.sup.-1 (0.005 in/min) is employed
as a characterization parameter in this invention. A measure of the
melt elasticity of a given system can also be obtained from these
rheological measurements. A type of flow instability known as melt
fracture is exhibited by many polymeric materials of high molecular
weight. This phenomenon is shear sensitive and thus will generally
exhibit itself at a given shear rate and temperature. The shear
rate for the onset of melt fracture indicates the upper shear rate
for processing a given material. This is used as a characterization
parameter for compounds employed in extrusion processing.
The metal sulfonate containing polymers at the higher sulfonate
levels possess extremely high melt viscosities and are thereby
difficult to process. The addition of ionic group plasticizers
markedly reduces melt viscosity and frequently enhances physical
properties.
To the neutralized sulfonated elastomeric polymer is added, in
either solution or to the crumb of the acid form of the sulfonated
elastomeric polymer, a preferential plasticizer selected from the
group consisting essentially of carboxylic acid having about 5 to
about 30 carbon atoms, more preferably about 8 to about 22 carbon
atoms, or basic salts of these carboxylic acids wherein the metal
ion of the basic salt is selected from the group consisting
essentially of aluminum, iron, antimony, lead or Groups I-A, II-A
I-B or II-B of the Periodic Table of Elements and mixtures thereof.
The carboxylic acids are selected from the group consisting
essentially of lauric, myristic, palmitic, or stearic acids and
mixtures thereof; e.g. zinc stearate, magnesium stearate, or zinc
laurate.
The preferential plasticizer is incorporated into the neutralized
sulfonated elastomeric polymer at about 0 to about 60 parts per
hundred by weight based on 100 parts of the sulfonated polymer,
more preferably at about 5 to about 40, and most preferably at
about 7 to about 25. The metallic salt of the fatty acid can also
be used as neutralizing agent. In the case of the neutralizing
agent and plasticizer being the identical chemical species,
additional metallic salt is added over the required levels of
neutralization. Alternatively, other preferential plasticizers are
selected from organic esters, phenols, trialkyl phosphates,
alcohols, amines, amides, ammonium and amine salts of carboxylic
acids and mixtures thereof. The preferred plasticizers are selected
from fatty acid or metallic salts of fatty acid and mixtures
thereof. The resultant neutralized sulfonated elastomeric polymer
with preferential plasticizer is isolated from the solution by
conventional steam stripping and filtration.
The resultant neutralized and plasticized sulfonated elastomer has
a viscosity at 200.degree. C. and a shear rate of 0.73 sec.sup.-1
of about 5.times.10.sup.4 poise to about 1.times.10.sup.6 poise,
more preferably of about 5.times.10.sup.4 poise to about
8.times.10.sup.5 poise and most preferably of about
8.times.10.sup.4 poise to about 8.times.10.sup.5 poise.
The neutralized sulfonated elastomeric polymer is blended with a
filler and a non-polar backbone process oil by techniques well
known in the art. For example, the blend composition can be
compounded on a two-roll mill. Other methods known in the art which
are suitable for making these compositions include those methods
employed in the plastic and elastomer industries for mixing polymer
systems. An excellent polymer blend composition of this invention
can be obtained through the use of a high shear batch intensive
mixer called the Banbury. Alternatively, economic advantages in
terms of time and labor savings can be obtained through the use of
a Farrel Continuous Mixer, a twin screw extruder, or tandem
extrusion techniques which are continuous mixing types of
equipment. The Banbury mixing device is the preferred batch type
mixer, and the twin screw extruder is the preferred continuous
mixer.
The fillers employed in the present invention are selected from
talcs, ground calcium carbonate, water precipitated calcium
carbonate, or delaminated, calcined or hydrated clays and mixtures
thereof. These fillers are incorporated into the blend composition
at about 25 to about 300 parts per hundred, more preferably at
about 25 to about 250 and most preferably at about 25 to about 200.
Typically, these fillers have a particle size of about 0.03 to
about 20 microns, more preferably about 0.3 to about 10, and most
preferably about 0.5 to about 10. The oil absorption as measured by
grams of oil absorbed by 100 grams of filler is about 10 to about
100, more preferably about 10 to about 85 and most preferably about
10 to about 75. Typical fillers employed in this invention are
illustrated in Table I.
TABLE 1
__________________________________________________________________________
Oil Absorption Specific Avg. Particle Filler Code # grams of
oil/100 grams of filler Gravity Size Micron pH
__________________________________________________________________________
Calcium carbonate Atomite 15 2.71 9.3 ground Calcium carbonate
Purecal U 35 2.65 .03-.04 9.3 precipitated Delaminated clay Polyfil
XB 30 2.61 4.5 6.5-7.5 Hydrated clay Suprex 2.6 2 4.0 Calcined clay
Icecap K 50-55 2.63 1 5.0-6.0 Talc magnesium Mistron Vapor 60-70
2.75 2 9.0-7.5 silicate
__________________________________________________________________________
The oils employed in the present invention are non-polar process
oils having less than about 2 wt. % polar type compounds as
measured by molecular type clay gel analysis. These oils are
selected from paraffinics ASTM Type 104B as defined in
ASTM-D-2226-70, aromatics ASTM Type 102 or naphthenics ASTM Type
104A, wherein the oil has a flash point by the Cleveland open cup
of at least 350.degree. F., a pour point of less than 40.degree.
F., a viscosity of about 70 to about 3000 ssu's at 100.degree. F.
and a number average molecular weight of about 300 to about 1000,
and more preferably about 300 to 750. The preferred process oils
are paraffinics. Table II illustrates typical oils encompassed by
the scope of this invention.
The oils are incorporated into the blend composition at a
concentration level of about 20 to about 200 parts per hundred,
more preferably at about 20 to about 175, and most preferably at
about 25 to about 150.
TABLE II ______________________________________ Viscos- % % % ity
Po- Aro- Satur- Type Oil Oil Code # ssu M.sub.n lars matic ates
______________________________________ Paraffinic Sunpar 115 155
400 0.3 12.7 87.0 Paraffinic Sunpar 180 750 570 0.7 17.0 82.3
Paraffinic Sunpar 2280 2907 720 1.5 22.0 76.5 Aromatic Flexon 340
120 -- 1.3 70.3 28.4 Naphthenic Flexon 765 505 -- 0.9 20.8 78.3
______________________________________
The filler to oil ratio in the present instant application is
critical and should be about 0.2 to about 2, more preferably 0.5 to
about 1.75 and most preferably about 0.75 to about 1.25.
Various other additives can be incorporated into the blend
compositions to improve the physical properties, the appearance,
the chemical properties of the formed elastomeric article or to
modify the processability of the blend compositions.
A crystalline polyolefinic thermoplastic can be incorporated into
the blend composition in minor proportions as a means for
modification of the rheological properties of the blend
compositions as well as the stiffness of the elastomeric article.
Typically, the crystalline polyolefinic thermoplastic is added to
the blend composition at a concentration level of about 0 to about
100 parts per hundred by weight based on 100 parts of sulfonated
polymer, more preferably at about 0 to about 75; and most
preferably at about 0 to about 50.
The crystalline polyolefin is characterized as a polymer of an
alpha-olefin having a molecular weight of at least 2,000,
preferably at least 10,000, and more preferably at least 20,000.
This material comprises substantially an olefin but may incorporate
other monomers, for example, vinyl acetate, acrylic acid, methyl
acrylate, ethyl acrylate, sodium acrylate, methyl methacrylate,
ethyl methacrylate, methacrylic acid, sodium methacrylate, etc. The
preferred polyolefins are selected from the group consisting of
polymers of C.sub.2 to C.sub.4 alpha-olefins. Most preferably, the
polyolefins are selected from the group consisting of polyethylene,
polybutene, polypropylene, and ethylene-propylene copolymers. It is
critical that the crystalline polyolefin have a degree of
crystallinity of at least 25% and most preferably at least 40%.
Both high and low density polyethylene are within the scope of the
instant invention. For example, polyethylenes having a density from
0.90 to 0.97 gms/cc are generally included. Polypropylene polymers
having intermediate and high densities are the preferred examples
of the polypropylene materials useful in the instant invention.
These materials will have a density from 0.88 to 0.925 gms/cc. The
polyethylene or polypropylene can also be combined as copolymers
thereof so long as adequate crystallinity is obtained in said
combination. Thus, block copolymers wherein polyethylene or
polypropylene is present in crystalline form are effective.
Zinc oxide can be incorporated into the blend as a whitening
pigment as well as a means for improving the ionic bonding force
between the sulfonate groups in the sulfonated elastomeric polymer.
The zinc oxide is incorporated into the blend composition at a
concentration level of about 0 to about 25 parts per hundred by
weight based on 100 parts of sulfonated polymer, more preferably
about 0 to about 15. Alternatively, a Rutile or Anatase titanium
dioxide can be employed as a whitening pigment.
A metallic hydroxide can be incorporated into the blend composition
as a means of further neutralizing any residual free acid in the
elastomeric compositions. The metallic hydroxide is incorporated at
a concentration level of about less than 5.0 parts per hundred
based on 100 parts of the neutralized sulfonated elastomeric
polymer, wherein the metal ion of the metallic hydroxide is
selected from Group II-A of the Periodic Table of Elements such as
barium, calcium, or magnesium.
A lubricant can be employed in the blend composition at a
concentration level of about 0 to about 20 parts per hundred based
on 100 parts of the neutralized sulfonated elastomeric polymers,
and more preferably about 0 to about 15. The lubricants of the
present instant invention are nonpolar paraffinic hydrocarbon waxes
having a softening point of about 135.degree. F. to about
220.degree. F., more preferably 150.degree. F., to 200.degree. F.,
wherein the wax has a number average molecular weight of about 1000
to about 4000, more preferably 1500 to 3500, and less than about 2
wt. % polar constituents. These lubricants modify the rheological
properties of the composition, improve the processability in
forming the elastomeric article and impart a shine or gloss to the
elastomeric article. Additionally, amorphous polypropylene can be
used as a lubricant.
Additionally, reinforcing fillers can be added as additives to the
blends of sulfonated polymer, filler and oil, wherein the
reinforcing filler is selected from the group consisting
essentially of silica, carbon black, or calcium silicate and
mixtures therein. These reinforcing agents are generally
characterized as having particle sizes below 0.1 microns and oil
absorption above about 100. These reinforcing fillers are
incorporated in the blend composition at about 0 to 50 parts per
hundred based on 100 parts of sulfonated polymer, more preferably 0
to 25. The ratio of filler to reinforcing agent is at least about
1, more preferably about 2, and most preferably about 3.
The ingredients incorporated into the blend compositions of the
present invention, in conjunction with the type of elastomeric
polymer, the degree of sulfonation, and the metal counterion of the
neutralized sulfonated elastomeric polymer, and the plasticizer
give materials processable by extrusion or injection molding
processes into elastomeric articles having the desirable physical
and rheological properties. These combined physical properties and
rheological processability characteristics were not previously
obtainable in the aforementioned U.S. patents and applications
previously incorporated herein by reference.
This present invention is related to two other applications filed
on the same day herewith, entitled "Elastomeric Compositions" Ser.
No. 855,757 and "Flow Modifiers for Sulfonated Elastomers" Ser. No.
855,726 in the names of J. Bock, R. D. Lundberg and H. S. Makowski.
The difference between the present invention and the "Elastomeric
Compositions" in both the resultant rheological and physical
properties of the compositions are unexpectedly different and
ideally applicable to different fabrication techniques for the
manufacture of vastly different elastomeric articles. The
invention, "Flow Modifiers for Sulfonated Elastomers" relates to
the use of hydrocarbon waxes used as flow modifiers and physical
property improvers which are also used in the present invention for
modification of flow properties of the compositions.
DETAILED DESCRIPTION
The advantages of both the rheological and physical properties of
the blend compositions of the present invention can be more readily
appreciated by reference to the following examples and tables.
Unless otherwise specified, all measurements are in parts per
hundred by weight.
EXAMPLE I--PREPARATION OF SULFONATED EPDM
One hundred grams of an EPDM terpolymer Vistalon 2504-20 was
dissolved under agitation in 1000 ml. of n-hexane at 40.degree. C.
The resultant cement was cooled to room temperature and 5.74 ml. of
acetic anhydride (60.75 mmoles) was then added. While stirring the
mixture, 2.1 ml. of 95% H.sub.2 SO.sub.4 (37.5 mmoles) was added
dropwise. The sulfonation reaction was quenched after 30 minutes
with 150 ml. of isopropanol. The acid form of the sulfonated
polymer was analyzed by Dietert Sulfur Analysis to have 33 meq. of
SO.sub.3 H groups per 100 grams of sulfonated polymer. To the
quenched sulfonated cement was added with stirring for thirty
minutes 25.6 grams (90 mmoles/100 grams of EPDM) of stearic acid. A
solution of 9.87 grams (90 meq./100 g. of EPDM) of zinc acetate
dihydrate dissolved in 25 ml. of distilled water was then added in
the cement and the cement stirred for an additional 30 minutes.
Antioxidant 2246 (0.5 grams) was then added to the cement. The
resultant plasticized, neutralized sulfonated EPDM terpolymer was
then isolated by steam stripping and drying on a rubber mill at
220.degree. F., wherein the sulfonated terpolymer has an apparent
viscosity at 0.73 sec.sup.-1 at 200.degree. C. of about
3.3.times.10.sup.5 poise. This material was incapable of being
injection molded on a low pressure Desma machine equipped with a
standard canvas footwear type mold.
EXAMPLE II--LOW PRESSURE INJECTION MOLDABLE COMPOSITIONS
(A) The Sulfonated EPDM Gum
The sulfonated EPDM gum was prepared in an identical manner as
described in Example I. Three compounds were prepared by combining
A with the ingredient type and concentration as shown in Table III
in a 60 cc. mixing chamber (manufactured by C. W. Brabender)
attached to a Plasticorder and equipped with Banbury type rotors.
The mixing chamber was heated to approximately 125-145.degree. C.
and an upside-down mix employed. This involved adding the filler,
oil (if present) sulfonated polymer, and plastic (if present)
sequentially. The rotor speed was set at 50 rpm and approximately 3
to 5 minutes after the addition of all ingredients, fluxing was
indicated by the torque chart of the Plasticorder. At approximately
seven minutes into the mix cycle, the rotor speed was increased to
100 rpm and the mix dumped at approximately 10 minutes in the form
of a coherent slab.
TABLE III ______________________________________ COMPOUNDS BASED ON
SULFO-EPDM Sample 1 2 3 ______________________________________
Ingredient A sulfonated EPDM 100 100 100 Process Oil-Sunpar 2280 50
85 Polyethylene (HDPE) 54 Polyethylene (LDPE) 25 Calcium Carbonate
(Atomite) 80 Calium Carbonate (Purecal U) 40 Talc - Mistron Vapor
15 Paraffin Wax (F 3504) 15 Zinc Oxide (Protox 166) 25 15 25
Magnesium Hydroxide 1.8 1.5 .57
______________________________________
The fillers employed in these mixes are described in Table I.
Atomite is a natural ground calcium carbonate, Purecal U is a
precipitated calcium carbonate, and the Mistron Vapor is a standard
magnesium silicate. The process oil employed was Sunpar 2280, a
paraffinic oil supplied by Sun Oil Co. The property characteristics
of the oil are described in Table II. The high density polyethylene
(HDPE) was supplied by Phillips and designated Marlex 6050
possessing an MFR of 6 while the low density polyethylene was
LD-610 (Exxon) and had an M.I. of 30.
(B) Determination of Low Pressure Injection Moldability
The compounds described in Part A were prepared in an effort to
determine a criterion for fabrication on a low pressure injection
molding machine such as a Desma or a Vulcaplast. Compound number 1,
a composition described in U.S. patent application No. 542,502 had
previously been observed to be injection moldable on a conventional
(high pressure) injection molder. However, in a low pressure Desma
injection molder equipped with a standard gated canvas sneaker
mold, it was not possible to fill the mold over the available range
of injection pressure, injection speed, and temperatures between
350.degree. to 450.degree. F. Compound 2 could only be molded at
the maximum available injection pressure and at a temperature of at
least 400.degree. F. Thus, compound 2 was barely fabricable in a
low pressure injection molder. Surprisingly, compound 3 was found
to be readily moldable at the midrange in injection pressure and at
a temperature between 350.degree. to 400.degree. F.
Determination of the melt rheological characteristics of compounds
1, 2 and 3 indicated the criterion for low pressure injection
moldability. The rheological measurements were determined on an
Instron Capillary Rheometer (plunger diameter=0.375", capillary
diameter=0.05", and length to diameter ratio of capillary=20). At a
temperature of 200.degree. C., the apparent viscosity was
determined at a range of steady shear rate values. Table IV shows
this rheological data for the compounds described above.
TABLE IV ______________________________________ RHEOLOGY OF S-EPDM
COMPOUNDS APPARENT VISCOSITY .times. 10.sup.-4 POISE AT 200.degree.
C. Compound No. 1 2 3 ______________________________________ Shear
Rate (sec.sup.-1) .74 31.1 8.3 3.2 7.4 11.1 2.4 1.4 74 3.6 .82 .43
294 -- .40 .20 740 -- .24 .12 Melt Fracture Onset 294 1470 3000
Shear Rate (sec.sup.-1) Injection (Low Pressure) NO Marginal Yes
Moldable ______________________________________
As shown in Table IV, the melt viscosities at 200.degree. C. of the
compounds differ substantially. However, the viscosity-shear rate
functionality appears to be similar for the compounds. For example,
the ratio of viscosity of 0.74 sec.sup.-1 shear rate to that at 74
sec.sup.-1 shear rate is approximately 9, 10 and 8 for compounds,
1, 2 and 3 respectively. Thus specifying the viscosity at a given
temperature and shear rate for a compound based on sulfo-EPDM
specifies approximately the viscosity over a range of shear rates.
Thus, it appears that specification of the viscosity at 0.74
sec.sup.-1 shear rate would yield the criterion for injection
moldability. Since compound 2 was barely injection (low pressure)
moldable, the maximum viscosity at 200.degree. C. and at 0.74
sec.sup.-1 shear rate will be taken to be 8.times.10.sup.4 poise.
Several subsequent evaluations have indicated the criticality of
this maximum viscosity value in terms of injection in low pressure
equipment commonly employed by the canvas footwear industry.
EXAMPLE III
(A) Preparation of Sulfonated Elastomer
Two EPDM terpolymers (V-2504 and V-2504-20) were sulfonated
according to the identical procedure which consist of dissolving
500 grams of the terpolymer into 5000 ml. of hexane of 40.degree.
C. for 5 hours with stirring. After cooling each cement to room
temperature, 36.38 ml. of acetic anhydride was added. After
stirring for 3 minutes, 13.33 ml. of 95% H.sub.2 SO.sub.4 was added
slowly (dropwise) to each solution and allowed to react for 30
minutes. Aliquots of these sulfonated elastomeric cements were
taken, the acid form of the sulfonated elastomers was isolated, and
Dietert Sulfur analysis was performed to determine the degree of
sulfonation. The cements of the acid form of the sulfonated
elastomers were simultaneously quenched and neutralized with a
solution of 62.56 grams of zinc acetate in 640 ml. of methanol and
24 ml. of distilled water. The neutralization reaction was allowed
to proceed for 30 minutes at which time 2.5 grams of Antioxidant
2246 (American Cyanamide) was added to the cement of each
neutralized sulfonated elastomer. Each neutralized sulfonated
elastomer was isolated from solution by steam stripping and
subsequently drying on a steam heated rubber mill at 200.degree. F.
The neutralized sulfonated elastomers of V-2504 (A-1) and V-2504-20
(A-2) each have about 45 meq. of sulfonate groups per 100 grams of
EPDM terpolymer. A-1 and A-2 was plasticized by adding a metal
stearate, namely zinc stearate. To A-1 was added 30 parts by weight
of zinc stearate per 100 parts of A-1. The resulting plasticized
sulfonated polymer will be designated A-1-P. To A-2 was added 20
parts by weight of zinc stearate per 100 parts of A-2. This polymer
will be designated A-2-P.
(B) Preparation of Compounds
Two compounds were prepared from each of the neutralized sulfonated
EPDM polymers described in part A and designated as A-1-P and
A-2-P. A 60 cc. mixing chamber (manufactured by C. W. Brabender)
attached to a Plasticorder and equipped with Banbury type rotors
was employed. The mixing chamber was heated to approximately
125.degree. C. and an upside down mix employed. This involved
adding the filler, oil, and sulfonated polymer sequentially. The
rotor speed was set at 50 rpm and 3 minutes after the addition of
all ingredients, fluxing was indicated by the torque chart. At
seven minutes into the mix cycle, the rotor rpm was raised to 100
and the mix dumped at approximately 10 minutes in the form of a
coherent slab.
The filler employed in these mixes was a natural ground calcium
carbonate supplied by Thompson, Weinman & Co. called Atomite.
The process oil employed was Sunpar 180, a paraffinic oil supplied
by Sun Oil Co. The property characteristics of the filler and oil
has been described in Tables I and II respectively. The
compositions of the compounds and their designation are shown in
the Table V below.
Upon attempting to prepare these formulations with the
unplasticized sulfonated polymers A-1 and A-2, it was observed that
fluxing did not occur in the mixing chamber after 20 minutes and
the resultant material dumped in the form of an incoherent powder.
The dispersion of the filler was extremely poor and could not be
fabricated by extrusion or injection molding. This illustrated the
criticality of the plasticizer.
TABLE V ______________________________________ COMPOSITIONS Sulfo-
Plasticizer nated Level Filler Polymer Zinc Stearate (Atomite) Oil
Compound Type Level (phr) Level (S-180) Designation
______________________________________ A-1 100 30 100 100 1 A-1 100
30 150 75 3 A-2 100 20 100 100 2 A-2 100 20 150 75 4
______________________________________
(C) Rheological and Physical Properties
The melt rheological characteristics of the neutralized sulfonated
ethylene propylene terpolymers and compounds derived therefrom were
determined by measurements on an Instron Capillary Rheometer
(plunger diameter=0.375", capillary diameter=0.05", length to
diameter ratio of capillary=20). At a temperature of 200.degree.
C., the apparent viscosity was determined at a range of steady
shear rate values. Table VI shows the rheological data for the gums
and compounds described above. The physical properties on these
materials are shown in Table VII.
TABLE VI
__________________________________________________________________________
EXTRUSION OF SULFONATED EPDM COMPOSITIONS APPARENT VISCOSITY (POISE
.times. 10.sup.-5) AT 200.degree. C. Sample No. A-1 A-2 A-1-P A-2-P
1 2 3 4
__________________________________________________________________________
Plasticizing none none yes yes yes yes yes yes 100 filler 100 150
150 filler Compounding none none none none 100 oil 100 75 75 oil
Shear Rate (sec.sup.-1) .73 6.03 7.67 .64 .75 1.29 1.37 7.3 1.89
2.30 .26 .28 .47 .52 73. .41 .54 .07 .08 .12 .13 291 .15 .19 .03
.03 .04 .05 728 .07 .10 .02 .02 .02 .03 Melt Fracture (sec.sup.-1)
291 146 1456 3000 1456 1456 Injection Moldable At Low Pressure none
none none none good good poor poor
__________________________________________________________________________
TABLE VII ______________________________________ PHYSICAL
PROPERTIES OF COMPOUNDS Compound 1 2 3 4
______________________________________ Tensile Properties (R.T.)
100% Mod. (psi) 335 325 505 470 300% Mod. (psi) 545 519 712 627
Tensile Strength at break 1564 1505 1452 1263 Elongation at break
(%) 640 620 563 555 Set at break (%) 50 50 44 44 Hardness (Shore A)
65 63 72 71 ______________________________________
This example illustrates some of the distinctive advantages of the
compositions of the instant invention over that in the prior art
and the range of molecular weights of the starting material which
can be employed in the instant invention. First, the neutralized
sulfonated polymers based on a precursor EPDM having a Mooney
viscosity (1+8 min.) at 212.degree. F. of 20 or 40 cannot be
injection molded as shown in Table VI. Attempting to compound these
materials with filler and oil results in an intractable material,
i.e. nonprocessable by injection molding. Plasticizing these
neutralized sulfonated polymers with a metal stearate (zinc
stearate) results in materials which are relatively stiff and
non-flexible and furthermore are not injection moldable on low
pressure machines. The addition of a particular mineral filler, and
process oil in the specified filler to oil ratio, in conjunction
with the plasticizer has produced materials which exhibit flow
characteristics necessary for low pressure injection molding. The
criticality of the filler to oil ratio is illustrated in the
rheological characteristics by the lack of melt strength and low
viscosity exhibited in the compounds wherein the filler to oil
ratio is 1 and the high viscosity and elasticity which preclude low
pressure molding exhibited in the compounds wherein the filler to
oil ratio is 2. The viscosity values for compounds 2 and 3 are just
below the critical maximum described in Example II. Thus, the
sulfonate level of approximately 45 meq per 100 g EPDM, the Mooney
viscosity (ML, 1+8, 212.degree. F.) of about 40 of the starting
EPDM and the filler to oil ratio of about 1 are near the maximum
limits necessary for producing a material which can be fabricated
on a low pressure injection molding machine.
The physical properties exhibited by compounds 2 and 3 as shown in
Table VII are excellent, illustrating that the Mooney viscosity of
the starting EPDM in the range of 20 to 40 (ML, 1+8, 212.degree.
F.) is operable.
EXAMPLE IV--SULFONATED BUTYL COMPOUNDS
(A) Preparation of Sulfonated Butyl
Exxon Butyl 365 having an unsaturation level of approximately 2.0
mole %, a Mooney viscosity (1+8) at 212.degree. F. of about 45 and
a viscosity average molecular weight of approximately 350,000,200 g
of which were dissolved in 3000 ml of hexane by heating to about
40.degree. C. for 6 hours. The polymer cement was cooled to room
temperature and 6.89 ml (72.9 mmoles) of acetic anhydride added and
stirred for 5 minutes. Next, 2.52 ml. (45.0 mmoles) of 95% sulfuric
acid was added dropwise and the solution stirred for an additional
30 minutes. A solution of 11.9 g of zinc acetate in 4 ml. of
distilled water and 160 ml. of methanol was added to the sulfonated
polymer in solution to terminate the sulfonation reaction and
neutralize the acid moiety. The neutralized sulfonated Butyl
polymer (A) was isolated by steam stripping and drying on a rubber
mill. Dietert sulfur analysis indicated a sulfonation level of
approximately 15 meq. per 100 g of Butyl.
(B) Compound Formulations
The neutralized sulfonated Butyl polymer (A) 100 parts by weight
was combined with 150 parts by weight of a finely divided calcium
carbonate (Atomite) and 75 parts by weight of a rubber process oil
(Sunpar 180) by the procedure described in Example III-B. This
compound was designated (B-1). The rheological properties of
Samples A and B-1 are illustrated in Table VIII.
TABLE VIII ______________________________________ EXTRUSION OF
SULFONATED BUTYL COMPOSITIONS APPARENT VISCOSITY (POISE .times.
10.sup.-5) AT 200.degree. C. Sample A B-1 B-2 B-3
______________________________________ Extrusion Rate (sec.sup.-1)
.73 8.08 5.21 .96 .86 7.3 1.75 1.30 .34 .22 73. .30 .34 .10 .09 291
.10 .14 .05 .04 728 .05 .08 .03 .02 Melt Fracture Shear Rate
(sec.sup.-1) 7.3 14 728 None
______________________________________
The neutralized sulfonated Butyl polymer (A) 100 parts by weight
was combined with 100 parts by weight of a finely divided calcium
carbonate (Atomite), 25 parts by weight of a rubber process oil
(Sunpar 180), 20 parts by weight of a low density polyethylene (LD
605, M.I. 7.5) and 20 parts by weight of zinc stearate by the
procedure described in Example III-B. This compound was designated
B-2.
The neutralized sulfonated Butyl polymer (A) 100 parts by weight
was combined with 40 parts by weight of a finely divided calcium
carbonate (Atomite), 30 parts by weight of a rubber process oil
(Sunpar 180), 20 parts by weight of a low density polyethylene (LD
605, M.I. 7.5), and 20 parts by weight of zinc stearate by the
procedures described in Example III-B. This compound was designated
B-3.
TABLE IX ______________________________________ PHYSICAL PROPERTIES
OF SULFONATED BUTYL COMPOSITIONS Sample B-1 B-2 B-3
______________________________________ Tensile Properties 100% Mod.
(psi) 87 305 220 300% Mod. (psi) 175 420 355 Tensile Strength (psi)
830 936 1150 Elongation at break (%) 1020 830 995 Hardness (Shore
A) 43 64 53 ______________________________________
This example illustrates several critical compositional variables
associated with this invention. This example demonstrates that a
hydrocarbon backbone other than EPDM, namely Butyl rubber can be
employed in the instant invention. Furthermore, at a sulfonate
level of approximately 15 meq. per 100 g Butyl, the resultant
compositions prepared by the teachings of this invention possess
excellent physical properties and flow properties. The necessity of
employing a plasticizer is further illustrated by the rheological
data in Table VIII. Both the neat sulfonated Butyl gum (A) and a
compound comprising the gum, process oil, and mineral filler (B-1)
result in materials which are not extrudable or injection moldable
due to both their high viscosity and high melt elasticity. However,
employing the combination of plasticizer and compounding
ingredients results in a material with markedly improved
rheological characteristics which is extrudable. Furthermore, both
the tensile modulus and compound hardness are substantially
improved as shown in Table IX.
EXAMPLE V
(A) Preparation of Sulfonated EPDM
An ethylene-propylene-ethylidene norbornene terpolymer (V-2504-20)
described in Example I, 200 g was dissolved in 2000 ml. of hexane.
At room temperature, 6.89 ml. of acetic anhydride was added to the
solution and stirred for 3 minutes. 2.52 ml. of 95% sulfuric acid
was then added dropwise and allowed to react for 30 minutes. An
aliquot of cement was taken and the polymer isolated for analysis
by Dietert Sulfur. The reaction was simultaneously terminated and
the acid neutralized by adding a solution of 11.58 g of zinc
acetate in 160 ml. of methanol and 4 ml. of distilled water. After
30 minutes, 1 g of antioxidant 2246 was added and the solution
allowed to stir for an additional 15 minutes. The neutralized
sulfonated ethylene-propylene terpolymer (A) was isolated by steam
stripping and drying on a rubber mill at 220.degree. F. The Dietert
Sulfur value indicated that 17 meq. of sulfonate had been
incorporated per 100 g of EPDM.
(B) Preparation of Compounds
Several compounds were prepared by the methods described in Example
II. The compositions are shown in Table X.
TABLE X ______________________________________ COMPOSITIONS Sample
1 2 3 4 ______________________________________ Ingredients A 100
100 100 100 Calcium Carbonate (Atomite) 150 50 50 50 Process Oil
(Sunpar 180) 75 25 25 25 Polyethylene (LD-400) 20 20 Zinc Stearate
20 20 ______________________________________
(C) Characteristics
The extrusion characteristics of the compositions described in Part
B of this Example were determined on an Instron Capillary Rheometer
as described previously. The results are shown in Table XI.
TABLE XI ______________________________________ EXTRUSION OF
MAGNESIUM NEUTRALIZED SULFO-EPDM COMPOSITIONS APPARENT VISCOSITY
(POISE .times. 10.sup.-5) AT 200.degree. C. Sample A 1 2 3 4
______________________________________ Extrusion Rate (see.sup.-1)
.73 32.5 9.2 1.2 1.2 10.0 7.3 5.58 1.8 .55 .59 1.96 73. .88 .30 .17
.18 .35 291 .26 .10 .07 .08 .12 728 .13 .05 .04 .04 .06 Melt
Fracture Shear Rate (sec.sup.-1) 7.3 14 1456 1456 146
______________________________________
The magnesium neutralized sulfo EPDM (A) is completely intractable
(not processable by extrusion or injection molding) as indicated by
the data in Table XI. Compounding with mineral filler and oil alone
(Sample #1) or in combination with low density polyethylene (Sample
#4) results in some improvement; however, the high viscosity and
high melt elasticity precludes these compositions from being
extruded or injection molded. However, the critical combination
(Sample #3) of mineral filler, process oil and plasticizer (namely
zinc stearate) converts the intractable system into one possessing
excellent flow characteristics. The non-criticality of the plastic
is illustrated by comparing Samples 2 and 3. The influence of the
plastic is shown by the physical properties in Table XII.
TABLE XII ______________________________________ TENSILE PROPERTIES
Compound A 1 2 3 4 ______________________________________ 100% Mod.
(psi) 76 273 209 199 300% Mod. (psi) 126 429 366 307 Tensile
Strength at Break (psi) 340 170 902 752 418 Elongation at break (%)
310 600 700 715 503 Hardness (Shore A) 45 66 61 62
______________________________________
The physical properties as shown in Table XII illustrate the
superiority of the compositions of the instant invention namely
Sample 2 and 3. As shown, the presence of polyethylene in Sample 2
acts to increase the hardness and modulate the tensile strength and
tensile modulus.
Surprisingly, the physical properties of the compositions of this
invention are superior to the original neutralized sulfonated gum
(Sample A). Hence, both the flow properties and physical properties
are enhanced simultaneously.
This example further demonstrates the low sulfonate level which can
be employed. Also, the use of different cations for neutralization
such as magnesium is illustrated.
EXAMPLE VI
(A) Compound Preparation
To 100 parts by weight of the sulfonated EPDM described in Example
II, was added 85 parts by weight of process oil (Sunpar 180), 40
parts by weight of a mineral filler (calcium carbonate--Purecal U)
25 parts by weight of zinc oxide (Protox 166), 5 parts by weight of
titanium dioxide, 15 parts by weight of wax (F-3504), 0.57 parts by
weight of magnesium hydroxide, and 2 parts by weight of
triethanolamine. This compound designated (VI-A) was prepared by
mixing the ingredients in a 1-A Banbury for approximately 10
minutes, at which time the mix was dumped at approximately
300.degree. F. The resultant material was then granulated.
(B) Shoe Molding
Compound VI-A was injection molded on a Desma rotary footwear
machine. The granulated feed was supplied to the reciprocating
screw section of the machine which was heated to a temperature of
approximately 385.degree. F. and injected into a footwear mold with
a canvas covered last. The last was heated to approximately
150.degree. F. The total cycle time for this operation was
approximately 1 minute, however the injection time was only 10 to
20 seconds. Some 300 canvas sneakers in varying sizes were produced
in this manner.
(C) Sneaker Evaluation
The Textile Services Division of United States Testing Company,
Inc. was commissioned to evaluate the performance of the sneakers
based on Sulfo-EPDM to commercially available materials. A triblock
polymer of styrene-butadiene-styrene compounded for footwear
applications and designated Kraton was evaluated along with a
plasticized PVC compound and a cured rubber compound. The following
tests were performed and the results herein described.
1. Abrasion Resistance
Specimens of the sole material of each sneaker were prepared and
tested in accordance with ASTM-1630. The results of these tests
were as follows:
______________________________________ ABRASION INDEX Sample Run 1
Run 2 Run 3 Average ______________________________________
Sulfo-EPDM Compound A 72.3 58.4 48.2 59.6 Vinyl 45.3 44.9 42.7 44.3
Kraton 24.8 25.5 28.6 26.3 Rubber 39.0 40.7 38.0 39.2
______________________________________
The results indicate that the compound based on Sulfo-EPDM has a
higher (better) abrasion index than that of plasticized Vinyl,
Kraton, or cured rubber.
2. Flex Resistance
Specimens of the sole of each sample were prepared and tested in
accordance with ASTM-D-1052 (Ross Flex), except that the aging
temperature was reduced to 100.degree. F.
The results of these tests were as follows:
______________________________________ Sample Cycles to Complete
Failure (cracking) ______________________________________ A No cut
growth of either specimen at 100,000 cycles Kraton 76,000; 36,400
Vinyl No cut growth of either specimen at 100,000 cycles Rubber
27,400; 14,800 ______________________________________
The results indicate a superiority of the compound based on
Sulfo-EPDM over that of Kraton and cured rubber in terms of flex
resistance.
3. Low Temperature Flex
One sneaker of each sample was placed in a cold chamber and the
chamber temperature was lowered to and maintained at 0.degree. F.
for a period of 2 hours. At the end of this period and while at the
test temperature, the sneakers were flexed manually to determine
the effects of storage at this temperature. The test was repeated
at -10.degree. F. chamber temperature increments to a final
temperature of -60.degree. F.
The results of these tests were:
______________________________________ Test Temperature, .degree.
F. A Vinyl Kraton Rubber ______________________________________ 0 S
S S S -10 S SLF S S -20 S MLF S S -30 S MLF S S -40 S U S S -50 S U
SLF S -60 SLF U SLF ______________________________________ Code: S
= Satisfactory flexibility SLF = Slight loss in flexibility MLF =
Moderate loss in flexibility U = Unsatisfactory (board-like)?
These results indicate the superiority of the sulfonated EPDM based
compound over Vinyl. Thus, in terms of overall flexibility as
measured by the Ross Flex (3) and low temperature flex (4), the
compound based on Sulfonated EPDM is superior to plasticized Vinyl,
Kraton and cured rubber.
4. Sole Hardness, Shore "A"
Shore "A" Hardness readings were obtained at five areas of each
sole, as received, that is, the surface was not buffed and the
values included any inherent "skin" hardness. The results of these
tests were as follows:
______________________________________ Sample Shore "A" Hardness
Average ______________________________________ A 50-50-47-51-51
50.0 Kraton 50-50-50-52-50 50.0 Vinyl 67-72-72-63-65 67.6 Rubber
62-65-60-61-60 61.6 ______________________________________
The compound based on Sulfonated EPDM (A) is similar in hardness to
that of the Kraton while the Vinyl and cured rubber compounds are
harder. The sulfonated EPDM compound (A) possesses a very desirable
rubbery feel characteristic particularly with regard to the vinyl
compound which is somewhat plastic like and stiff in nature.
5. Coefficient of Friction
A six inch length of the sole of each sample, measured from the
toe, was removed from the sneaker and used as the "sled" for the
coefficient of friction test against waxed asphalt tile. Tests were
conducted on an Instron Model TTC testing machine employing a 20
pound range and a crosshead speed of 12 inches per minute. The sled
weight was 20 pounds.
The static (initiate motion) and dynamic (maintain motion)
coefficients of friction were calculated from the data:
______________________________________ COEFFICIENT OF FRICTION
Static Dynamic Sample Range Average Range Average
______________________________________ A .72-.77 .74 .70-.71 .71
Kraton .49-.51 .50 .50-.51 .51 Vinyl .55-.64 .58 .52-.63 .56 Rubber
.45-.46 .46 .41-.44 .42 ______________________________________
The coefficient of friction data indicate that the compound based
on sulfonated EPDM has a higher static and dynamic coefficient of
friction in comparison to Kraton, Vinyl and cured rubber. In a
footwear sole application, this would provide better traction and
stopping characteristics. This would be particularly advantageous
on waxed floor surfaces and wet surfaces such as wet grass.
In general, the physical characteristics of the compound based on
sulfonated EPDM is superior to those based on Kraton, plasticized
Vinyl and cured rubber as illustrated in this example.
* * * * *